Terminal-contact rivet construction and method of assembly thereof

ABSTRACT

A terminal contact rivet construction for use in a thermostatic switch and including a sleeve that cooperates with a rivet for securing a terminal strip and contact element to the housing of said switch, said sleeve and rivet further acting to prevent loosening of the terminal strip and contact element upon expansion or contraction of the switch housing due to temperature differentials experienced in the operation of said switch.

United States Patent AND METHOD OF ASSEMBLY THEREOF 6 Claims, 3 DrawingUS. Cl.

Int. Cl

Field of Search Figs.

............................... 337/381, 200/166 CT, 337/354, 339/219 R..ll0lh 37/04, HOlh 37/52, HOlr 9/20 CT, 168 A; 339/219, 220

References Cited UNITED STATES PATENTS 5/1967 Bolesld y 2/1966 Huffman2/1941 Furnas FOREIGN PATENTS 9/1961 Switzerland Primary ExaminerBernardA. Gilheany Assistant Examiner-Dewitt M. Morgan Attorney-Salter andMichaelson 337/354X 337/354X 200/166 CT ABSTRACT: A terminal contactrivet construction for use in a thermostatic switch and including asleeve that cooperates with a rivet for securing a terminal strip andcontact element to the housing of said switch, said sleeve and rivetfurther acting to prevent loosening of the terminal strip and contactelement upon expansion or contraction of the switch housing due totemperature differentials experienced in the operation of said switch.

liilii 64 E/METAL TERMINAL-CONTACT RIVET CONSTRUCTION AND METHOD OFASSEMBLY THEREOF BACKGROUND OF THE INVENTION The present invention hasapplication in thermostatic switch constructions that are employed insmall appliances such as coflee percolatorsand the like.

The thermostat switch as used in a small electrical appliance isnormally constructed with interior contact elements that areelectrically interconnected to terminal strips that are secured to theswitch housing exteriorly thereof. A bimetallic element is usuallyemployed in such a switch and is heat responsive to make or breakcontact between the contact elements within the switch housing. Prior tothe instant invention, the terminal strips were interconnected to thecontact elements by means of a rivet that projected through an openingformed in the housing of the switch. However, after a period of use, theterminal strips and interior contact elements had a tendency to becomeloosened on the rivet because of the temperature differentialsexperienced in the operation of the switch as contained in theelectrical appliance. When such a situation occurred, proper electricalcontact between the interior contact element and the external terminalstrip was difiicult to obtain, thereby resulting in malfunction of thethermostat.

SUMMARY OF INVENTION The present invention relates to a thermostaticswitch construction that includes a housing formed of a nonconductingmaterial and which has an interior chamber formed therein. At least oneopening is formed in the housing that communicates with the interiorchamber and a terminal strip is located at the outer end of the openingexteriorly of the housing and a contact element is located at the innerend of the opening in said chamber. Fixed within the opening in thehousing is a metallic sleeve, the metallic sleeve cooperating with ametallic rivet projecting therethrough to anchor the terminal stripexteriorly of the housing and to fix the contact element within thechamber. The terminal strip and the contact element are permanently andsecurely fixed in position by deforming the outer ends thereof andproviding a flange on the inner end of the sleeve that cooperates withthe head of the rivet, wherein the terminal strip and contact elementare secured between the sleeve and rivet. Thus, since the contact stripand element are sandwiched between the sleeve and rivet, they cannotbedislodged therefrom and even if the housing of the thermostatic switchis subjected to temperature changes which results in loosening of theterminal-contact assembly in the housing, the terminal switch andcontact element are still maintained in firm position between the rivetsleeve.

Accordingly, it is an object of the invention to provide a thermostaticswitch construction that includes a tenninal strip and contact elementthat are securely held in position in the housing of the switch.

Another object of the invention is to provide a sleeve and rivet for usein a thermostatic switch construction that cooperate to permanentlysecure a terminal strip and contact element in place, rivet and sleevethereby preventing loosening of the terminal strip and contact elementin their fixed position regardless of the temperaturedifferentials'experienced by the switch in the operation thereof. Stillanother object is to provide a thermostatic switch construction thatincludes sleeve and rivet that are deformed at the outer ends thereof tofur a terminal strip therebetween, and that further cooperate to lock acontact element between a flange of the sleeve and the head of therivet.

Still another object is to teach a method of securing a terminal stripand contact element in place in a thermostatic switch construction, thesteps of the method including the deforming of the outer endsof thesleeve and rivet to lock a terminal strip therebetween.

Other objects, features and advantages of the invention shall becomeapparent as the description thereof proceeds when considered inconnection with the accompanying illustrative drawing.

DESCRIPTION OF THE DRAWING In the drawing which illustrates the bestmode presently contemplated for carrying out the present invention:

FIG. 1 is a partial sectional view of a body portion of a thermostaticswitch construction showing a terminal strip and contact element priorto the assembly thereof to the switch houss;

FIG. 2 is a partial sectional view similar to FIG. 1- showing theassembly operation of a terminal strip and contact element; and 7 FIG. 3is an amplified sectional view of FIG. 1, illustrating the finishedassembly of the terminal strip and contact element to the housing of theswitch construction.

DESCRIPTION OF THE INVENTION Referring now to the drawing, thethermostatic switch construction embodied in the present invention isillustrated and is generally indicated at 10. As contemplated for use,the thermostatic switch construction 10 of the present invention hasapplication in small electrical appliances such as a coffee percolatoror the like. However, it will be understood that the concept of theinvention that embodies the securement of a terminal strip and contactelement in place between a sleeve and rivet as will be describedhereinafter, is not limited to thermostatic switches, although thepurpose of the invention does contemplate the use of a terminal contactrivet assembly in an environment that is subject to temperaturedifferentials.

As shown in FIG. 3, the thermostatic switch construction embodied in thepresent invention includes a housing generally indicated at 11 that isdefined by a body portion I2 and a base 13 that is secured to the bodyportion by an annular clamping member 14, as will be describedhereinafter. The body portion 12 of the housing 1 l is formed of a heatresistant phenolic resin and has a generally circular cross-sectionalconfiguration, an interior chamber 15 being formed therein. Extendingthrough the body portion 12 and communicating with the interior chamber15 is a passage or opening 16, while a passage or opening 17, having asmaller axial dimension, is also formed in the body portion 12 in spacedrelation with respect to the opening 16. As will be described, terminalstrips 18 and 20 are fixed to the body portion 12 exteriorly thereof,and are adapted to be electrically interconnected to interior contactelements 22 and 24. The contact element 24 is formed with an integralspaced parallel portion 25, a contact button 27 being joined to theportion 25 and normally making contact with the contact element 22. Aswill be set forth hereinafter, a temperature responsive bimetallicelement 29, located in a recess 33 of the base 13,is adapted to urge aplunger 31 into engagement with the parallel portion 25 of the contactelement 24 for moving the contact button 27 out of engagement with thecontact element 22, thereby breaking the electrical circuit asestablished between the terminal strips 18 and 20 through theirrespective contact elements 22 and 24.

In order to provide for permanent electrical communication between theterminal strips I8 and 20 and their respective contact elements 22 and24, metallic sleeves 26 and 28 are located in the openings 16 and 17 andcooperate with rivets 30 and 32 for securing the terminal strips andcontact elements to the housing 11. As indicated in FIGS. 1 and 2, theassembly of the terminal strips 18 and 20 and the contact elements 22and 24 to the housing 11 is initiated by inserting the terminal strips18 and 20 over the ends of pins 34, only one of which is illustrated inFIGS. 1 and 2. The body portion 12 is placed over the pins which arereceived in openings 16 and 17, the terminals strips 18 and 20 beingoriented in channels 44 and 46 that are formed in an end wall of thebody portion. The metallic sleeves 26 and 28 are inserted over the pins34 in the openings 16 and 17 respectively and, as illustrated in FIG. 1,the outermost end of each sleeve engages the corresponding terminalstrip. The contact elements 22 and 24 are then placed over the ends ofthe pins 34 within the chamber 15.

It is understood that the diameter of the pins 34 is somewhat less thanthe openings 16 and 17 through which they extend, and thus the sleeves26and 28 are receivable on the pins 34 as located within the openings 16and 17. The sleeves 26 and 28 are each formed with an interior flange 38and 40 respectively, the flanges cooperating with heads 42 and 43respectively of the rivets 30 and 32 to secure the contact elements 22and 24 in place within the switch housing, as will be described.

It will also be noted that the outer end of the body portion is providedwith the channels 44 and 46 in which the terminal strips 18 and arereceived, the channels 44 and 46 being adapted to prevent lateralshifting of the terminal strips 18 and 20 after they have been locked inplace on the body portion 10 by the rivets 30 and 32. As furtherillustrated in FIG. 1, the openings 16 and 17 are countersunk asindicated at 48 and 50 at the outer ends thereof, the countersunkportions 48 and 50 communicating with the channels 44 and 46respectively. With the sleeves 26 and 28 mounted in position within theopenings 16 and 17, the outermost ends of the sleeves are locatedslightly above the countersunk portions 48 and 50, and, as will bedescribed, are deformed to conform to the countersunk portions when therivets 30 and 32 are inserted in place.

In the assembly operation, the rivets 30 and 32 are inserted within thesleeves 26 and 28 respectively in the direction of the arrows as seen atthe bottom of the rivets in FIG. 1. As the rivets are fed into thesleeves 26 and 28 they displace the pins 34, which are shown in FIG. 1in the full-line position as being removed entirely from the bodyportion 12 when the rivets are fully inserted into their respectivesleeves. As the rivets 30 and 32 displace the pins 34, the pins reach astop position and, as continued pressure is exerted on the rivets (seeFIG. 2), the outermost ends of the sleeves 26 and 28 are deformed byflaring outwardly as indicated at 52 and 54 in FIG. 3. The outermost endof each of the rivets 30 and 32 is formed with a shell configurationhaving a relatively thin wall as indicated at 56 and 58in FIG. I, andwhen the pressure is applied to the thin walls of the shells against thepins 34, the walls are deformed so as to be bent over the terminalstrips 18 and 20 through which the rivets 30 and 32 extend. Asillustrated in FIG. 3, annular bent over wall portions 56 and 58cooperate with the deformed portions 52 and 54 of the sleeves 26 and 28to lock the terminal strips 18 and 20 therebetween. At the same timethat the rivets 30 and 32 eject the pins 34, the heads of the rivets 42and 43 capture the contact elements 22 and 24 therebetween and theflanges 38 and 40 of the sleeves 26 and 28 respectively. Thus when thepins 34 have been completely ejected from the body portion 10 and thepressure is applied to the rivets to bend over the thin wall portions ofthe rivets as indicated at 56 and 58, the locking of the rivets 30 and32 in place against the terminal strips 18 and 20, also locks thecontact elements 22 and 24 between the heads 42 and 43 of the rivets andthe flanges 38 and 40 of the sleeves 26 and 28 respectively.

The assembly of the thermostatic switch is completed by locating thebase 13 in engagement with the body portion 12, a shoulder 61 of thebase being located against the adjacent edge of the body portion 12. Thebase 13 is formed with an interiorly projecting portion 62 that isreceived within the chamber 12 of the body portion, an opening 64 beingformed in the projecting portion 62. The recess 33 that is formed in thebase 13 receives the pin 31 therein which also projects through theopening 64 for engagement with the contact element 24. The bimetallicelement 29 is received in an annular groove 72 formed in the base 13 andis locked in place by the annular locking member 14 that is secured tothe body portion 12 and the base 13. It is seen that in the operation ofthe device, the bimetallic element 29 is responsive to changes in thetemperature, and is flexed upwardly to the dotted line position asillustrated in FIG. 2 to move the pin 31 upwardly,

thereby causing the contact element 24 to be removed from electricalengagement with the contact element 22. This breaks the circuit betweenthe terminal strips 18 and 20 and will control the temperature of theappliance in which the thermostatic switch is located.

It is also contemplated to assemble the terminal strips and contactelements by preassembling the sleeves in the housing and partiallydeforming the outer ends of the sleeves prior to inserting the rivetstherein. The rivets are then inserted in place and the outer shell wallsrolled over as indicated above.

It is understood that the thermostatic switch construction 10, asembodied in the present invention is subjected to temperaturedifferentials during the operation thereof. Should the body portion 12expand or contract during this operation, the effect thereof will not inany way influence the securement of the terminal strips 18 and 20 to thesleeves 26 and 28 and rivets 30 and 32. Thus proper electricalcommunication between the terminal strips 18 and 20 will be maintainedwith their respective contact elements 22 and 24 at all times. Shouldthe sleeves 26 and 28 become loose within the openings 14 and 16 uponexpansion of the body portion 12, the contact elements 22 and 24 and thetenninal strips 18 and 20 will still remain effectively locked betweentheir respective sleeves and rivets.

I claim:

1. A thermostatic switch construction, comprising a housing having abody portion formed of a nonconducting material and in which an interiorchamber is formed, at least on opening formed in said body portion thatcommunicates with said interior chamber, a terminal strip located at theouter end of said opening exteriorly of said body portion and a contactelement located at the inner end of said opening in said chamber, ametallic sleeve fixed in said opening, and a rivet projecting throughsaid contact element, said sleeve and said terminal strip, and having aninner end located in said chamber and an outer end located at the outerend of said opening, the outer end of said rivet being free fromengagement with any externally applied fastener, said sleeve and rivetbeing deformable at their outer ends for engaging relation with saidterminal strips on opposite sides thereof and cooperating together attheir outer ends to anchor said terminal strip therebetween exteriorlyof said body portion, said sleeve having an outwardly extending flangeat its inner end cooperating with the inner end of said rivet to fixsaid contact element therebetween within said chamber, wherein saidterminal strip and contact element are permanently and securely fixed inposition regardless of the expansion or contraction of said body portiondue to temperature differentials in the operation of said switchconstruction.

2. In a thermostatic switch construction as set forth in claim 1, saidsleeve having a flange formed on the inner end thereof and said rivetincluding a head, said contact element being captured between the headof said rivet and the flange of said sleeve.

3. In a thermostatic switch construction as set forth in claim 1, theouter end of said sleeve being flared outwardly and the outer end ofsaid rivet being turned over, wherein said terminal strip is anchoredbetween the flared outer end of said sleeve and the turned over end ofsaid rivet.

4. In a thermostatic switch construction, a housing having a bodyportion formed of a nonconducting material and in which an interiorchamber is formed, at least one opening formed in said body portion thatcommunicates with said interior chamber, a terminal strip located at theouter end of said opening exteriorly of said body portion and a contactelement located at the inner end of said opening in said chamber, ametallic sleeve fixed in said opening, and a river projecting throughsaid sleeve and cooperating therewith to anchor said terminal stripexteriorly of said body portion and to fix said contact element withinsaid chamber, wherein said terminal strip and contact element arepermanently and securely fixed in position regardless of the expansionor contraction of said body portion due to temperature difierentials inthe operation of said switch construction, the outer end of said sleevebeing flared outwardly and the outer end of said rivet being turnedover, wherein said terminal strip is anchored between the flared outerend of said sleeve and the turned-over end of said rivet, the bodyportion being countersunk at the outer end of said opening, the flaredportion of said sleeve being received in the countersunk area of saidbody portion.

5. In a method of securing a terminal strip in a thermostatic switchconstruction, wherein the terminal strip is interlocked between a sleeveand a n'vet that extend through an opening formed in the body portion ofsaid switch construction, comprising the steps of locating a pin in saidopening, mounting said terminal strip on said pin exteriorly of saidbody portion, inserting said sleeve around said pin in said opening, andfeeding said rivet through said sleeve simultaneously displacing the pinfrom said opening and deforming the outer ends of said rivet and sleeveto anchor said terminal strip therebetween.

6. In a method as set forth in claim 5, said sleeve being deformed byflaring the outer end thereof, and said rivet being deformed by turningover the outer end thereof wherein said terminal strip is capturedbetween the flared end and turned over end as said rivet displaces saidpin from said opening.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,614,702 Dated October 19, 1971 InVentOr(S) Walter S. Vargas It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Claim 1, line 3, "on" should be --one- Signed and sealed this 16th dayof April 19714..

(SEAL) Attest:

EDWARD M.FLETGHER,JR. C. I-IARSHALL DANN Attesting Officer Commissionerof Patents

1. A thermostatic switch construction, comprising a housing having abody portion formed of a nonconducting material and in which an interiorchamber is formed, at least on opening formed in said body portion thatcommunicates with said interior chamber, a terminal strip located at theouter end of said opening exteriorly of said body portion and a contactelement located at the inner end of said opening in said chamber, ametallic sleeve fixed in said opening, and a rivet projecting throughsaid contact element, said sleeve and said terminal strip, and having aninner end located in said chamber and an outer end located at the outerend of said opening, the outer end of said rivet being free fromengagement with any externally applied fastener, said sleeve and rivetbeing deformable at their outer ends for engaging relation with saidterminal strips on opposite sides thereof and cooperating together attheir outer ends to anchor said terminal strip therebetween exteriorlyof said body portion, said sleeve having an outwardly extending flangeat its inner end cooperating with the inner end of said rivet to fixsaid contact element therebetween within said chamber, wherein saidtermInal strip and contact element are permanently and securely fixed inposition regardless of the expansion or contraction of said body portiondue to temperature differentials in the operation of said switchconstruction.
 2. In a thermostatic switch construction as set forth inclaim 1, said sleeve having a flange formed on the inner end thereof andsaid rivet including a head, said contact element being captured betweenthe head of said rivet and the flange of said sleeve.
 3. In athermostatic switch construction as set forth in claim 1, the outer endof said sleeve being flared outwardly and the outer end of said rivetbeing turned over, wherein said terminal strip is anchored between theflared outer end of said sleeve and the turned over end of said rivet.4. In a thermostatic switch construction, a housing having a bodyportion formed of a nonconducting material and in which an interiorchamber is formed, at least one opening formed in said body portion thatcommunicates with said interior chamber, a terminal strip located at theouter end of said opening exteriorly of said body portion and a contactelement located at the inner end of said opening in said chamber, ametallic sleeve fixed in said opening, and a river projecting throughsaid sleeve and cooperating therewith to anchor said terminal stripexteriorly of said body portion and to fix said contact element withinsaid chamber, wherein said terminal strip and contact element arepermanently and securely fixed in position regardless of the expansionor contraction of said body portion due to temperature differentials inthe operation of said switch construction, the outer end of said sleevebeing flared outwardly and the outer end of said rivet being turnedover, wherein said terminal strip is anchored between the flared outerend of said sleeve and the turned-over end of said rivet, the bodyportion being countersunk at the outer end of said opening, the flaredportion of said sleeve being received in the countersunk area of saidbody portion.
 5. In a method of securing a terminal strip in athermostatic switch construction, wherein the terminal strip isinterlocked between a sleeve and a rivet that extend through an openingformed in the body portion of said switch construction, comprising thesteps of locating a pin in said opening, mounting said terminal strip onsaid pin exteriorly of said body portion, inserting said sleeve aroundsaid pin in said opening, and feeding said rivet through said sleevesimultaneously displacing the pin from said opening and deforming theouter ends of said rivet and sleeve to anchor said terminal striptherebetween.
 6. In a method as set forth in claim 5, said sleeve beingdeformed by flaring the outer end thereof, and said rivet being deformedby turning over the outer end thereof wherein said terminal strip iscaptured between the flared end and turned over end as said rivetdisplaces said pin from said opening.